The present invention relates to a device for changing a wire netting in a filter device for synthetic resins.
When synthetic resins are melted and extruded from an extruding machine, a breaker plate is used to exclude impurities in the raw materials. The breaker plate has a plurality of small openings and is equipped with a circular wire netting on the surface thereof facing the extruding port of the extruding machine. The melted synthetic resins are screened through the wire netting and the impurities can be excluded. However, the breaker plate is set in a die body. Therefore, when the wire netting must be changed, the extruding machine operation must be stopped and the die body must be opened, after which the wire netting can be changed. Therefore, it has been very troublesome to change a used wire netting to a new wire netting.
To avoid the above described trouble, a screen change device was provided which can change the screen during extrusion as is disclosed in Japanese Patent Publication No. 4179 of 1973. The screen change device is composed of a screen carrier and a fixed body around which the screen carrier can rotate in contact therewith. However, in this screen device, a plurality of screen carriers must be rotated by means of hydraulic mechanism and it becomes necessary to equip the screen device with another driving motor than the motor that drives the extruding machine. Therefore, a large floor to support the other motor and the extruding machine becomes necessary. Besides, it was necessary to change an opening for an inlet and an opening for an outlet respectively at the same time when the plurality of screen carriers are changed. Accordingly, the mechanism of the screen device becomes very complex. From this complexity many defects arise.